Two of the BBC's most senior news and current affairs executives attacked the corporation's plans yesterday for a Comic Relief-style day of programming on environmental issues, saying it was not the broadcaster's job to preach to viewers.

The event, understood to have been 18 months in development, would see stars such as Ricky Gervais and Jonathan Ross take part in a "consciousness raising" event, provisionally titled Planet Relief, early next year.

But, speaking at the MediaGuardian Edinburgh International Television Festival yesterday, Newsnight's editor, Peter Barron, and the BBC's head of television news, Peter Horrocks, attacked the plan, which also seems to contradict the corporation's guidelines. Asked whether the BBC should campaign on issues such as climate change, Mr Horrocks said: "I absolutely don't think we should do that because it's not impartial. It's not our job to lead people and proselytise about it." Mr Barron said: "It is absolutely not the BBC's job to save the planet. I think there are a lot of people who think that, but it must be stopped."

Planet Relief appears to contradict BBC guidelines on impartiality. In June a BBC-endorsed report set out 12 principles on impartiality, warning that the broadcaster "has many public purposes of both ambition and merit - but joining campaigns to save the planet is not one of them".

A BBC spokeswoman said: "This idea is still in development and the intention would be to debate the issue and in no way campaign on a single point of view."

Meanwhile, in a session at the festival yesterday titled How Green is TV, the documentary producer Martin Durkin attacked the BBC as stifling debate on climate change. Durkin, whose film The Great Global Warming Swindle attracted a large number of complaints when it was shown on Channel 4 this year, said: "The thing that disturbs me most is that the BBC has such a leviathan position ... that if it decides that it is going to adopt climate change as a moral purpose, I have got a lot of trouble with that. I don't think it is the role of the BBC to spend my money on a moral purpose."